A Rare Uranyl(VI)–Alkyl Ate Complex [Li(DME)_1.5]₂[UO₂(CH₂SiMe₃)₄] and Its Comparison with a Homoleptic Uranium(VI)–Hexaalkyl

Abstract

Ein seltener Tetraalkyluranyl‐„at“‐Komplex 1 wurde zum Vergleich mit einem UVI‐Hexaalkyl 2 hergestellt und charakterisiert. Sowohl 1 als auch 2 zeigen präzedenzlose Hochfrequenz‐13C‐NMR‐Verschiebungen (siehe Bild); für 2 entspricht dies einem Rekord für diamagnetische einkernige Komplexe. Relativistische DFT‐Rechnungen belegen, dass diese extremen Verschiebungen auf Spin‐Bahn‐Effekte infolge einer signifikanten Beteiligung des f‐Orbitals an der U‐C‐Bindung zurückzuführen sind.

Isolation and characterization of a covalent CeIV-Aryl complex with an anomalous 13C chemical shift

“…The same functional previously provided excellent ligand chemical shifts in actinide complexes 40,44 . PBEh-40 produced a similar cerium electronic structure (Mulliken/natural charge of +2.43/ +2.66, 4f 0.58 5d 0.59 NBO natural electron configuration, Ce − C aryl WBO of 0.37) as B3LYP.…”

“…Previously reported Ce IV − C bonds contain 8-13% Ce contribution 25 . Ce tends to be less covalent than U VI (U VI − C bonds 22-29% U) but similar to Th IV (Th IV − C aryl bonds 10-15%) 9,25,38,40 . In the remaining σ and π bonds with the N and O atoms, Ce contributes about 3-4% weight, suggesting that these bonds are mainly ionic.…”

Comparison of the Reactivity of 2‐Li‐C6H4CH2NMe2 with MCl4 (M=Th, U): Isolation of a Thorium Aryl Complex or a Uranium Benzyne Complex

“…The large chemical shift observed for these nuclei may be due to spin orbit coupling, which is significant in the actinides. [12] Complex 1 crystallizes in the monoclinic space group C2/c (Figure 1). Complex 1 exhibits a dodecahedral coordination geometry, in which the two orthogonal trapezoids are defined by N1-C1-N2-C2 and N1*-C1*-C2*-N2*.…”

Lewis Base Activation by Uranium(III) Complexes

“…In 3-py-Si , the 29 Si­{ 1 H} NMR spectrum contains a signal at −6.8 ppm for the (Me 3 Si) 3 Si atom as well as a signal at −51.0 ppm for the (Me 3 Si) 3 Si atom. As a comparison from a direct U­(IV)–Si­(SiMe 3 ) 3 interaction [ (Me 3 Si) 3 Si: −9.83, (Me 3 Si) 3 Si : −137.09 ppm], 1-THF and 3-py-Si are not as influenced by paramagnetic spin–orbit coupling , as indicated by the shift differences of the (Me 3 Si) 3 Si atom. In addition, 1-THF and 2-DME also resonate outside the tabulated range of other silicon-containing U­(III) compounds (−116 to −247 ppm) .…”